Study on the influence of cross-sectional area and zeta potential on separation for hybrid-chip-based capillary electrophoresis using 3-D simulations

Hybrid chips combing microchips with capillaries have displayed particular advantages in achieving UV-vis and mass spectroscopic detection. In this work, systematic 3-D numerical simulations have been carried out to explore the influence of junction interface cross-sectional area and ζ-potential distribution on sample band broadening in hybrid-chip electrophoresis separation. In this case, the ratio of cross-sectional area of chip to capillary channel (S(ratio) ) is used as the parameter of the variation in junction interface cross-sectional area. Theoretical simulations demonstrated that the decrease of the S(ratio) would increase the separation efficiency in the hybrid-chip-based CE with uniform ζ-potential distribution. ζ-potential distribution along the axial direction of the channel also affects mass transport in hybrid-chip-based CE. Therefore, the effect of ζ-potential distribution has been considered in the 3-D simulation. Theoretical simulation results reveal that ζ-potential distribution rather than the interface cross-sectional area variation (S(ratio) ) controls the sample band broadening and manipulates sample separation efficiency in the hybrid-chip-based CE with non-uniform ζ-potential distribution. Both the theoretical simulations and experimental results show that optimal hybrid-chip CE separation efficiency can be achieved at S(ratio) =1.     

Synthesis of hyperolactones A and C

Hyperolactones A ( 1 ) and C ( 3 ) have been synthesized starting from (S)‐malic acid by a straightforward route. The unique spirolactone skeleton was efficiently constructed by one‐pot reaction as a key step. The absolute stereochemistry of hyperolactones was unambiguously established by this synthesis.     

微波消解-HG-AFS测定大米中痕量砷

研究了微波消解-氢化物发生-原子荧光光谱法测定大米中痕量砷的方法。建立了大米用微波消解的最佳分析条件，试验了酸、预还原剂用量等对测定砷的影响，并讨论了大米中其他伴生元素对测定的干扰情况，确定了原子荧光光谱仪的参数设置和最佳氢化反应条件。检出限为0．04ng／mL。此法测定标准物质大米粉(GBW 08502)中砷的含量，其结果与证书值相吻合，相对标准偏差为2．5％，回收率为93．9％-115．0％。     

Development of standards for reliable surface analyses by ISO technical committee 201 on surface chemical analysis

The need for reliable surface analyses together with quality‐management requirements for analytical laboratories led the International Organization for Standardization (ISO) to form its Technical Committee (TC) 201 on Surface Chemical Analysis in 1991. This article describes the organization of TC 201, the strategies that have been found useful for identifying and assessing possible projects for new international standards, and the 57 international standards and other documents prepared to date by TC 201. Standards have now been developed for Auger‐electron spectroscopy, glow‐discharge spectroscopy, various types of scanning probe microscopy, secondary‐ion mass spectrometry, sputter‐depth profiling, total‐reflection X‐ray fluorescence spectroscopy, X‐ray photoelectron spectroscopy, and X‐ray reflectometry. In addition, standards have been developed with definitions of terms used in surface chemical analysis; the handling, preparation of specimens for surface analysis; information and data‐transfer formats; and methods for determining the lateral resolution of beam‐based methods of surface analysis. Copyright © 2014 John Wiley & Sons, Ltd.     

碲化铋取向纳米柱状薄膜热导率测量

将热电材料制作成纳米柱状薄膜结构是一种理论上能有效降低热导率、从而大幅提升热电优值的操控手段。但是随之而来的问题是纳米柱状薄膜热导率的精确获取困难,因为常规的热物性测试手段已无法适用于该类表面多孔、厚度为微米量级结构热输运特性的表征。本文提出利用3ω方法可实现Bi_2Te_3取向纳米柱状薄膜热导率实验表征的测量结构,并且获得了纳米柱状薄膜的热导率和热扩散率值。该方法有望用于微米厚纳米柱状薄膜结构热输运性能的实验评价。     

激光二极管抽运氦气冷却钕玻璃叠片激光放大器热致波前畸变和应力双折射的数值模拟和实验研究

热效应仍是限制激光放大器向高功率、高光束质量进一步发展的瓶颈问题, 高效的热管理是抑制热效应的重要技术途径. 研究了基于激光二极管抽运氦气冷却的钕玻璃叠片激光放大器的热效应. 利用有限元数值模拟的方法, 分析了钕玻璃的温度、应力应变和应力双折射分布, 并计算了热致波前畸变和退偏损耗, 与实验结果符合得较好, 在热沉积为0.7 W/cm³的条件下, 6片钕玻璃总的热致波前畸变为6.77λ , 最大退偏量大于90%.     

Thermally treated bare gold nanoparticles for colorimetric sensing of copper ions

We demonstrate a sensitive and rapid colorimetric assay for selective detection of copper ions based on the strong coordination between Cu(II) ions and the tetrahydroxyaurate anions [Au(OH)₄]^? on the surface of thermally treated bare gold nanoparticles (GNPs). The method for making the unmodified GNPs is simple and results in a nanomaterial with a highly specific response to Cu(II). The thermal treatment of the bare GNPs and the recognition of Cu(II) ions is accomplished in a single step within 5 min. The presence of Cu(II) causes the color to change from red to purple-blue. The limit of detection (LOD) is 0.04 μM of Cu(II) when using UV–vis spectrometry and ratioing the absorbances at 650 and 515 nm, respectively. The method also is amenable to bare eye (visual) inspection and in this case has an LOD of 2.0 μM of Cu(II).

基于声表面波技术实现数字微流体多基片间输运

建立了声表面波实现多基片间输运微流体的新方法.由3个128(0)YX-LiNbO3压电基片组成,一个基片为接口基片,另两个为工作基片,每个基片光刻一个中心频率为27.5 MHz叉指换能器和一个反射栅.采用微量进样器将待输运的数字微流体进样到工作基片2,调节接口基片使得其与工作基片2位于同一高度,并使其间隙尽可能小,在工...     

Heterologous expression characteristics of Trichoderma viride endoglucanase V in the silkworm, Bombyx mori L

Efficient degradation of cellulose needs a synergistic reaction of the cellulolytic enzymes, which include exoglucanases, endoglucanases, and β-1,4-glucosidase. In this study, we used an improved Bac-to-Bac/BmNPV baculovirus expression system, which lacks the virus-encoded chitinase cathepsin (v-cath) genes of Bombyx mori nucleopolyhedrovirus (BmNPV), to express the endoglucanase V (EG V) gene from Trichoderma viride in silkworm BmN cells and silkworm larvae, and analyzed the characteristics of the recombinant enzyme in silkworm larvae. The result showed that an around 36-kDa protein was visualized in BmN cells at 48 h after the second-generation recombinant mBacmid/BmNPV/EG V baculovirus infection. The crude enzyme extract from the recombinant baculoviruses-infected silkworms exhibited a significant maximum activity at the environmental condition of pH 5.0 and a temperature of 50 °C, and increased 39.86% and 37.76% compared with that from blank mBacmid/BmNPV baculovirus-infected silkworms and normal silkworms, respectively. It was stable at pH range from 5.0 to 10.0 and at temperature range from 40 to 60 °C. The availability of large quantities of EG V that the silkworm provides might greatly facilitate the future research and the potential application in industries.     

Looking-glass synergistic pharmacological chaperones: DGJ and L-DGJ from the enantiomers of tagatose

The enantiomers of tagatose are converted to L-DGJ [a noncompetitive inhibitor of human lysosome α-galactosidase A (α-Gal A), K(i) 38.5 μM] and DGJ [a competitive inhibitor of α-Gal A, K(i) 15.1 nM] in 66% yield. L-DGJ and DGJ provide the first examples of pharmacological chaperones that (a) are enantiomeric iminosugars and (b) have synergistic activity with implications for the treatment of lysosomal storage disorders and other protein deficiencies.